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In the wild, a worm drop looks like any other mud ball bobbing at the bottom of a pond. But if you poke a humble worm droplet, it will react in a way a mud ball would never do, turning into a noodle shape that a Pastafarian might mistakenly divine.

This is how Saad Bhamla discovered the first drop of worms in a pond in California. A bioengineer in the Georgia Institute of Technology’s school of chemical and biomolecular engineering, Dr. “It comes alive when you poke it with a stick,” Bhamla said. Dr. Bhamla’s encounter with the worm drop haunted him for years (in a good way, he says) until he set up his own lab and needed the first project.

California landworms, soft and thin threads that are as surreal red as grocery store meat, often live in seasonal ponds. When time is good, a worm is just a worm moving on its own. When times are bad, a worm should become a blob, entangling with hundreds or thousands of other worms into a slimy, writhing ball. And like a moving ball of thread, the worm drop can move as a single unit, away from predators or stress.

“They stay braided and twisted into this unified unit that’s creeping around,” said Chantal Nguyen, a postdoctoral associate and physicist at the BioFrontiers Institute at the University of Colorado Boulder.

But how does a worm achieve and maintain blobdom? In a recent study in the journal Limits in Physics, Dr. Nguyen and Dr. A group of researchers, including Bhamla, have unraveled the secrets of the blob’s mobility. They did this by constructing a computer model of entangled California landworms.

“It was pretty scary and pretty shocking, but it was also beautiful,” said Albert Kao, a postdoctoral researcher who studies the collective behavior of wormspots at the Santa Fe Institute in New Mexico. The simulation “likely opens a way forward for new kinds of models for entangled systems,” he added.

From time immemorial, humans have seen groups of animals move in unison: a flock of starlings, a flock of fish, midge swarmand heavy metal heads moss. But few people have had the privilege or interest in observing wormspots.

A bead of worms acts as a solid and liquid, like a ball of dough or a shampoo glob. Only about 10 worms are required to create a consistent blob. A drop of about 100,000 worms resembles a piece of (red) pizza dough. There is no known limit to how many worms can form a blob, except perhaps your imagination.

When Serena Ding, a researcher at the Max Planck Institute for Animal Behavior, first saw a photo of black wormspots, her mind was blown. Unrelated to the newspaper, Dr. “I was shocked at first,” Ding said. “Then I was disgusted and then fascinated.”

Studying bubble formation in the widely studied nematode Caenorhabditis elegans, Dr. Ding described C. elegans spots as “overlapping strongly, like a bowl of spaghetti noodles.” Black worm spots “look more like spaghetti noodles falling on the floor,” he said, frowning in a Zoom call. “C. elegans is named because it is elegant. They are not just….”

But Dr. It was precisely this black worm drop that captured Bhamla’s heart. To him, the bubbles feel like pizza dough flowing through your fingers. “But it’s made of worms,” ​​he said. “It’s like a nightmare come alive.”

In February, Dr. Bhamla and a group of researchers described the dynamics of wormspots in the journal. Proceedings of the National Academy of Sciences.

For this article, Yasemin Özkan-Aydin, now a robotics engineer at the University of Notre Dame, led the experiments. Dr. When Özkan-Aydin pulled the worms out of the water, they went on individual quests to return to the water. If they couldn’t find water, they formed water droplets; it was a mess that allowed them to survive 10 times longer than individual worms outside of water.

“The reason they clump together is not out of the kindness of their hearts, but because they use it to protect the rest of the individuals from desiccation,” said Simon Garnier, a biologist at the New Jersey Institute of Technology who was not involved in the research. .

Dr. Özkan-Aydın also found that wormspots were removed from stress factors such as light and heat en masse. A worm droplet on the hot plate will move to a cooler section and a worm droplet under a spotlight will act as a droplet. But if the plate is heated to about 100 degrees Fahrenheit, if it’s too hot for the worms to survive, the drip will quickly dissolve. In smaller numbers, the blob propels itself, dividing the labor, outstretched, pulling the worms forward, and the worms curling behind, reducing friction. Larger wormspots, which are more difficult to visualize due to the density of their components, can move in more complex ways.

Orit Peleg, a University of Colorado physicist and author of the new paper in Frontiers in Physics, first saw the spots during a visit to Georgia Tech. Stains Dr. It reminded Peleg of the biological polymers he once studied, such as DNA, but the spots were visible to the naked eye and were made up of worms. Dr. Peleg, Dr. When he shows Nguyen a video of a block of worms solving the maze, Dr. Nguyen needed no further persuasion to study the worms.

Dr. Nguyen designed a simulated model of both individual and spotted blackworms, containing small spots of 20 identical worms. Each worm was represented by a string of taut beads that could bend and stretch like a real worm. Dr. Nguyen incorporated a bonding force into the model that encourages the model worms to stick together in the form of a two-dimensional drop.

Dr. Kao, Dr. “That’s not what the real worm does, and yet they reproduce the behavior of the blob visually and quantitatively,” Nguyen said of his colleagues.

In early prototypes of the model, the simulated worms were not cooperative, either separating themselves from the blob or piling up in one place. Dr. Nguyen struggled with the stickiness of the worms and the strength of their individual drives, until at last he found a sweet spot where the wormdrop could move as a whole.

Dr. Peleg said the model shows us that there is “no clear distinction” between living and inanimate materials, adding that researchers hope the model will inspire entangled robots made of flexible materials.

The researchers plan to expand their model to three dimensions to gain more insight into how worms tangle, twist, and weave together. Dr. Garnier suggested that this expansion could answer one of his burning questions about the blob: where in the blob a worm would most want to be.

The best spot might be close enough to the surface to grab resources, but deep enough that the worm isn’t the first line of defense. “Collective systems have to deal with these trade-offs,” he said. “When we have too many, not enough cake for everyone, things start to get ugly.”

Fortunately, Dr. Bhamla’s lab has tens of millions of black worms ready to bubble. The coronavirus pandemic and drought have made worms a hot commodity, so Dr. Bhamla’s lab is growing on its own. Some days he discovers that a braided chain of worms is crawling along a wall in an attempt to break out of jail.

In the morning, when the researchers turn on the overhead lights, all the free-roaming worms run together in droplets until they adjust to the light and relax. Dr. Bhamla said, “’What party was going on when it was dark and cold there?’ I’m like,” he said. “It’s not hard to fall in love with them.”